Owing to recent and unprecedented progress in the field, cortical motion processing has become a model system for studying the relationship between neural activity and perceptual state. As a result, we are now in an excellent position to probe the neural bases of some phenomena in motion perception that have been of longstanding interest to perceptual psychologists. The aim of the proposed research is to investigate the functions of cortical visual areas in motion perception through a combined application of neurophysiological and psychophysical techniques. One important issue concerns the "rules" used by cortical motion detectors to establish spatio-temporal continuity of moving images. Recent evidence indicates that certain low-level image features, such as color, can influence this motion correspondence process. In essence, the system appears to exploit real-world image properties in order to reduce ambiguity that might otherwise jeopardize correspondence detection. Psychophysical and neurophysiological experiments have been designed to identify and characterize the neural systems mediating these perceptual phenomena. The results should provide clues to the level of image representation used by cortical motion detectors. A second issue of great interest concerns the neural mechanisms and events that underlie the integration of locally derived motion signals. Psychophysical and neurophysiological experiments will address the ways in which cortical motion detectors are affected by stimulus variables that are found to control perceptual integration of motion signals. The results of these experiments should provide the first insights into how the motion integration process is dynamically controlled and how it, thereby, mediates our perceptual experience. Both phases of this project will focus initially on the contribution of cortical visual area MT in alert animals. A major emphasis will be placed upon obtaining evidence for links between perceptual and neural events by performing psychophysical and neurophysiological experiments under identical conditions. The long-term goal of the proposed project is to obtain information that will aid in the treatment and prevention of neurologic and ophthalmic disorders of vision caused by trauma, disease and developmental defects. The aims are pertinent to a variety of clinical applications including the development of prostheses for the visually handicapped and treatment programs for perceptual deficits, as well as many non-clinical applications such as the design and implementation of machine-based visual systems for automated object recognition and methods for improving human performance on complex visuomotor tasks.